USBAudioToI2S - Plays USB Audio packets through external DAC (Cir…

Users » csorbag » Code » USBAudioToI2S

Sheldon Cooper / Mbed 2 deprecated USBAudioToI2S

Plays USB Audio packets through external DAC (Cirrus Logic CS4344). Simple demo code, don't expect a sophisticated I2S library. HW setup: mbed DIP 5 (I2STX_SDA) -> DAC SDIN (Serial Audio Data Input) mbed DIP 6 (I2STX_WS) -> DAC LRCK (Left Right Clock) mbed DIP 7 (I2STX_CLK) -> DAC SCLK (External Serial Clock Input) mbed DIP 30 (I2SRX_CLK) -> DAC MCLK (Master Clock) also needed an extra USB connector wired to mbed. Does not work with built-in USB. Code needs a bit of clean up.

Dependencies: mbed

I2S.cpp@1:12e8ee1b7ea2, 2012-04-16 (annotated)

Committer:: csorbag
Date:: Mon Apr 16 08:32:38 2012 +0000
Revision:: 1:12e8ee1b7ea2
Parent:: 0:bf9e7b99dda5

Who changed what in which revision?

User	Revision	Line number	New contents of line
csorbag	0:bf9e7b99dda5	1	#include "I2S.h"
csorbag	0:bf9e7b99dda5	2	#include "MODDMA.h"
csorbag	0:bf9e7b99dda5	3
csorbag	0:bf9e7b99dda5	4
csorbag	0:bf9e7b99dda5	5	volatile uint32_t counter=0;
csorbag	0:bf9e7b99dda5	6
csorbag	0:bf9e7b99dda5	7	DigitalOut led3(LED3);
csorbag	0:bf9e7b99dda5	8
csorbag	0:bf9e7b99dda5	9	//Serial *global_out;
csorbag	0:bf9e7b99dda5	10	MODDMA dma;
csorbag	0:bf9e7b99dda5	11	MODDMA_Config *dmaconfig;
csorbag	0:bf9e7b99dda5	12
csorbag	0:bf9e7b99dda5	13	void TC0_callback(void);
csorbag	0:bf9e7b99dda5	14	void TC1_callback(void);
csorbag	0:bf9e7b99dda5	15	void TC2_callback(void);
csorbag	0:bf9e7b99dda5	16
csorbag	0:bf9e7b99dda5	17	#define BUFFER_SIZE 2048
csorbag	0:bf9e7b99dda5	18
csorbag	0:bf9e7b99dda5	19	int16_t buffer[BUFFER_SIZE];
csorbag	0:bf9e7b99dda5	20
csorbag	0:bf9e7b99dda5	21	int16_t transferSize;
csorbag	0:bf9e7b99dda5	22
csorbag	0:bf9e7b99dda5	23	int16_t bufferStart, nextToPlay;
csorbag	0:bf9e7b99dda5	24	volatile int16_t playing = 0;
csorbag	0:bf9e7b99dda5	25
csorbag	0:bf9e7b99dda5	26	volatile int16_t moreToPlay=0;
csorbag	0:bf9e7b99dda5	27
csorbag	0:bf9e7b99dda5	28	void setup(Serial *out) {
csorbag	0:bf9e7b99dda5	29
csorbag	0:bf9e7b99dda5	30	global_out = out;
csorbag	0:bf9e7b99dda5	31
csorbag	0:bf9e7b99dda5	32	bufferStart = nextToPlay = (int16_t *)buffer;
csorbag	0:bf9e7b99dda5	33
csorbag	0:bf9e7b99dda5	34	LPC_SC->PCONP \|= 1 <<27; // Enable I2S
csorbag	0:bf9e7b99dda5	35	LPC_SC->PCLKSEL1 \|= 1 << 22; // Set Clock to CCLK
csorbag	0:bf9e7b99dda5	36	// Reset i2s
csorbag	0:bf9e7b99dda5	37	LPC_I2S->I2SDAO = (1 << 4);
csorbag	0:bf9e7b99dda5	38	LPC_I2S->I2SDAO = 0;
csorbag	0:bf9e7b99dda5	39
csorbag	0:bf9e7b99dda5	40
csorbag	0:bf9e7b99dda5	41
csorbag	0:bf9e7b99dda5	42	LPC_I2S->I2SDAO = 1 /* Number of bytes 16bit / \| 0xF << 6 / Word select half perion - 1 /;// \| 1 << 3 / Stop bit */;
csorbag	0:bf9e7b99dda5	43	LPC_I2S->I2SDAI = 1 /* Number of bytes 16bit / \| 0xF << 6 / Word select half perion - 1 /;// \| 1 << 3 / Stop bit */;
csorbag	0:bf9e7b99dda5	44
csorbag	0:bf9e7b99dda5	45
csorbag	0:bf9e7b99dda5	46	LPC_PINCON->PINSEL0 \|= 01 << 14 /* I2STX_CLK / \| 01 << 16 / I2STX_WS / \| 01 << 18 / I2STX_SDA */;
csorbag	0:bf9e7b99dda5	47	LPC_PINCON->PINSEL0 \|= 01 << 8 /* I2SRX_CLK / \| 01 << 10 / I2SRX_WS / \| 01 << 12 / I2SRX_SDA */;
csorbag	0:bf9e7b99dda5	48
csorbag	0:bf9e7b99dda5	49	// Set all to neither pull-up, nor pull-down
csorbag	0:bf9e7b99dda5	50	LPC_PINCON->PINMODE0 \|= 2 << 14 /* I2STX_CLK / \| 2 << 16 / I2STX_WS / \| 2 << 18 / I2STX_SDA */;
csorbag	0:bf9e7b99dda5	51	LPC_PINCON->PINMODE0 \|= 2 << 8 /* I2SRX_CLK / \| 2 << 10 / I2SRX_WS / \| 2 << 12 / I2SRX_SDA */;
csorbag	0:bf9e7b99dda5	52
csorbag	0:bf9e7b99dda5	53
csorbag	0:bf9e7b99dda5	54	// Cirrus Logic CS4344 specific frequency settings
csorbag	0:bf9e7b99dda5	55	LPC_I2S->I2STXRATE = 125 /* Y_divider / \| 4 << 8 / X_divider */;
csorbag	0:bf9e7b99dda5	56	LPC_I2S->I2SRXRATE = 125 /* Y_divider / \| 32 << 8 / X_divider */;
csorbag	0:bf9e7b99dda5	57
csorbag	0:bf9e7b99dda5	58	int rxbitrate = 1;
csorbag	0:bf9e7b99dda5	59	LPC_I2S->I2STXBITRATE = 1;
csorbag	0:bf9e7b99dda5	60	LPC_I2S->I2SRXBITRATE = rxbitrate;
csorbag	0:bf9e7b99dda5	61
csorbag	0:bf9e7b99dda5	62
csorbag	0:bf9e7b99dda5	63	LPC_I2S->I2STXMODE = (0 << 0) \| (1 << 3);
csorbag	0:bf9e7b99dda5	64	LPC_I2S->I2SRXMODE = (0 << 0) \| (1 << 3);
csorbag	0:bf9e7b99dda5	65
csorbag	0:bf9e7b99dda5	66
csorbag	0:bf9e7b99dda5	67	// Start trasnmit
csorbag	0:bf9e7b99dda5	68	LPC_I2S->I2SDAO &= (~(1 << 3));
csorbag	0:bf9e7b99dda5	69	LPC_I2S->I2SDAI &= (~(1 << 3));
csorbag	0:bf9e7b99dda5	70
csorbag	0:bf9e7b99dda5	71	LPC_I2S->I2SDMA1 = (1 << 1) /* Enable transit / \| (0 << 16) / Transmit FIFO level */;
csorbag	0:bf9e7b99dda5	72
csorbag	0:bf9e7b99dda5	73
csorbag	0:bf9e7b99dda5	74	out->printf("I2S Setup complete\n");
csorbag	0:bf9e7b99dda5	75
csorbag	0:bf9e7b99dda5	76	dmaconfig = new MODDMA_Config;
csorbag	0:bf9e7b99dda5	77	dmaconfig
csorbag	0:bf9e7b99dda5	78	->channelNum ( MODDMA::Channel_0 )
csorbag	0:bf9e7b99dda5	79	// ->srcMemAddr ( (uint32_t) &buffer1 )
csorbag	0:bf9e7b99dda5	80	->dstMemAddr ( 0 )
csorbag	0:bf9e7b99dda5	81	//->transferSize ( 2500 )
csorbag	0:bf9e7b99dda5	82	->transferType ( MODDMA::m2p )
csorbag	0:bf9e7b99dda5	83	->transferWidth ( 1 )
csorbag	0:bf9e7b99dda5	84	->srcConn ( 0 )
csorbag	0:bf9e7b99dda5	85	->dstConn ( MODDMA::I2S_Channel_0 )
csorbag	0:bf9e7b99dda5	86	->dmaLLI ( 0 )
csorbag	0:bf9e7b99dda5	87	->attach_tc ( &TC1_callback )
csorbag	0:bf9e7b99dda5	88	;
csorbag	0:bf9e7b99dda5	89
csorbag	0:bf9e7b99dda5	90	out->printf("DMA Setup complete\n");
csorbag	0:bf9e7b99dda5	91
csorbag	0:bf9e7b99dda5	92	}
csorbag	0:bf9e7b99dda5	93
csorbag	0:bf9e7b99dda5	94
csorbag	0:bf9e7b99dda5	95	void play(int16_t *buf,int16_t length) {
csorbag	0:bf9e7b99dda5	96
csorbag	0:bf9e7b99dda5	97
csorbag	0:bf9e7b99dda5	98	moreToPlay = 1;
csorbag	0:bf9e7b99dda5	99
csorbag	0:bf9e7b99dda5	100	if (nextToPlay - bufferStart + length >= BUFFER_SIZE) {
csorbag	0:bf9e7b99dda5	101	nextToPlay = bufferStart;
csorbag	0:bf9e7b99dda5	102	}
csorbag	0:bf9e7b99dda5	103
csorbag	0:bf9e7b99dda5	104	memcpy(nextToPlay,buf,length*sizeof(int16_t));
csorbag	0:bf9e7b99dda5	105
csorbag	0:bf9e7b99dda5	106	transferSize=length;
csorbag	0:bf9e7b99dda5	107
csorbag	0:bf9e7b99dda5	108
csorbag	0:bf9e7b99dda5	109	// Wait for end of playing previous packet
csorbag	0:bf9e7b99dda5	110	while (playing) {};
csorbag	0:bf9e7b99dda5	111
csorbag	0:bf9e7b99dda5	112	playing = 1;
csorbag	0:bf9e7b99dda5	113	moreToPlay = 0;
csorbag	0:bf9e7b99dda5	114
csorbag	0:bf9e7b99dda5	115	dmaconfig->srcMemAddr ( (uint32_t) nextToPlay );
csorbag	0:bf9e7b99dda5	116	dmaconfig->transferSize ( length / 2);
csorbag	0:bf9e7b99dda5	117	nextToPlay+=length*sizeof(int16_t);
csorbag	0:bf9e7b99dda5	118
csorbag	0:bf9e7b99dda5	119
csorbag	0:bf9e7b99dda5	120	dma.Prepare(dmaconfig);
csorbag	0:bf9e7b99dda5	121
csorbag	0:bf9e7b99dda5	122
csorbag	0:bf9e7b99dda5	123	}
csorbag	0:bf9e7b99dda5	124
csorbag	0:bf9e7b99dda5	125
csorbag	0:bf9e7b99dda5	126
csorbag	0:bf9e7b99dda5	127	void TC1_callback(void) {
csorbag	0:bf9e7b99dda5	128
csorbag	0:bf9e7b99dda5	129	// Get configuration pointer.
csorbag	0:bf9e7b99dda5	130	MODDMA_Config *config = dma.getConfig();
csorbag	0:bf9e7b99dda5	131
csorbag	0:bf9e7b99dda5	132	// Finish the DMA cycle by shutting down the channel.
csorbag	0:bf9e7b99dda5	133	dma.Disable( (MODDMA::CHANNELS)config->channelNum() );
csorbag	0:bf9e7b99dda5	134
csorbag	0:bf9e7b99dda5	135
csorbag	0:bf9e7b99dda5	136	// Clear DMA IRQ flags.
csorbag	0:bf9e7b99dda5	137	if (dma.irqType() == MODDMA::TcIrq) dma.clearTcIrq();
csorbag	0:bf9e7b99dda5	138
csorbag	0:bf9e7b99dda5	139	playing = 0;
csorbag	0:bf9e7b99dda5	140
csorbag	0:bf9e7b99dda5	141	if (!moreToPlay) {
csorbag	0:bf9e7b99dda5	142	LPC_I2S->I2STXFIFO = 0x0;
csorbag	0:bf9e7b99dda5	143	led3 = !led3;
csorbag	0:bf9e7b99dda5	144	}
csorbag	0:bf9e7b99dda5	145	}

Repository toolbox

Export to desktop IDE

Build repository

Repository details

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	16 Apr 2012
Imports:	142
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	3
Followers:	9

I2S.cpp@1:12e8ee1b7ea2, 2012-04-16 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning